Cam operated extractor



Dec., 24, i957 D. P. GRovER ErAL M7173 CAM OPERATED ExTRAcToR Filed March 11, 1954 HTTDRNEYS CAM OPERATED EXTRACTOR Donald P. Grover, Chicago, and Bernard Stevens, Skokie, Ill., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Application March 11, 1954, Serial No. 415,712

1 Claim. (Cl. 42-68) Our invention relates to an electrically fired revolvertype automatic gun and more particularly to an extractor therefor. I

Such a gun ordinarily comprises a recoil unit provided with a barrel and slidable on a receiver, and an actuator slidably disposed with respect to the recoil unit. The recoil unit also includes a rotatable drum provided with cartridge chambers. Rollers and grooves are provided on the drum and the actuator, respectively, for engagement during operation of the actuator to successively index the chambers to a firing position of the drum aligned with the barrel.

The cartridge drum of the gun usually includes five chambers each of which dwells in four nontiring positions during one rotation of the drum while the cartridges in the remainder of the chambers are successively red. The chambers are loaded with cartridges by a feeder before they reach the ring position and the cases of the spent cartridges are removed from the chambers in a case extraction position immediately following the tiring position.

The extractor currently used for the gun described includes a pawl for projecting into the extraction groove Of a case chambered in the extraction position. The pawl is secured to the upper end of a shaft journaled in the recoil unit, and a spring secured to the pawl and the recoil unit is wound around the shaft to bias the pawl towards the rear face of .the drum.

A cam on the lower end of the shaft and a striker on the actuator are provided for engagement -to rotate the pawl and remove the case from the drum during forward operation of the actuator. The cam and the striker are adapted for a decreasing radius of engagement during extraction to provide an increasing case extraction speed.

In this device, the pawl is displaced from the drum during the last portion of the forward actuator stroke and during an equal rst portion of the following rearward actuator stroke after which the spring is required to return the pawl to engagement with the drum to be in position for engagement with the extraction groove of a cartridge case rotating to the extraction position. In this device a pawl spring strong enough to return the pawl in time to engage the incoming cartridge causes the pawl to rebound from vthe drum several times during each cycle to wear out the spring prematurely and cause the gun to fail.

It is, therefore, an object of `our invention to provide an extract-or adapted to return the pawl Ito stable engage ment with the drum before the spent case is rotated into the extraction position.

Another object of our invention is to provide an extractor of the type described with a cam for restoring and controlling restoration of the pawl to engagement with the drum.

Other aims and objects will appear from the following explanation of our invention.

In carrying out our invention, the cam of an extractor pf the kind described is provided with an additional YSec- 2,817,173; Patented Dec. 24, 1957 tion and the actuator of the gun is provided with a corresponding guide to aid the spring to return the pawl to the drum.

High-speed camera studies ofthe improved device show that the guide controls in forcing the pawl to return to normal position and the pawl spring stabilizes engagement of the pawl with the drum.

For a better understanding of our invention, reference is made to the following description and the accompanying drawing in which:

Fig. 1 is a partial elevation of an automatic gun incorporating our invention;

Fig. 2 is a view along line 2 2 of Fig.I 1;

Fig'. 3 is a view along line 3 3 of Fig. 2;

Fig. 4 is a view along line 4 4 of Fig,- 2 with the actuator in battery position;`

Figs. 5 and 6 are viewsalong line 4 4 of Fig. 2. during restoration `of the pawl to normal position; and

Fig. 7 is a view along line 4 4 of Fig. 2 at the beginning of extraction.

According to the drawing, an automatic gun 12 includes a recoil unit 14 slidable `on a receiver 16 by means of feet 18 and an actuator 20 slidable with respect to recoil unit 14 by means of feet Z2.

A barrel 24 is secured to recoil unit 14 and a drum 26 is mounted on a shaft 28 journaled in the recoil unit. Drum 26 includes spaced cartridge chambers supplied with cartridges by a feeder shown generally at 30 and the drum is rotatable to convey the chambers to a six oclock tiring position thereof aligned with barrel 24. A chamber is shown in the extraction position 32 of the drum immediately adjacent the tiring position. Spent cartridge case 36 is shown in extraction position chamber 32.

A pawl 38 for projecting into extractor groove 40 of case 36 is splined to a shaft 42 journaled in recoil unit 14. Pawl 38 is biased to a normal position against rear face 44 of drum 26 by a spring 46 wrapped around shaft 42 and secured to recoil unit 14. Minimum clearance is provided 'between shaft 42 and drum 26 to limit the required length of pawl 38 and hence to limit the time required for recovery of the pawl to the normal position after displacement therefrom.

A cam 48, secured to the lower end of shaft 42, includes a surface 50 for engagement with a surface 52 of a striker S4 secured to actuator 20.

Actuator 20 is forced rearwardly, responsive to discharge -of a cartridge chambered in the drum tiring position and then forwardly responsive to the energy given up by the rotating drum and to a lesser extent to the energy given up by the actuator springs to rotate case 36 of the spent cartridge to extraction position 32 with extractor groove 40 enclosing the end of pawl 38 as shown in Fig. 3.

Drum 26 is maintained at rest rotationally during the substantially 21/2 inches of forward stroke of the actuator immediately preceding battery position to allow for extraction of spent cartridge cases, and the drum remains at rest during an equal length of the next rearward stroke of the actuator from the battery position. During the portion of the forward stroke of the actuator that the drum is at rest, surface 52 engages cam surface 50 to rotate pawl 38 and remove case 36 from drum 26.

Pawl 38 remains displaced from drum 26 when actuator 20 is in battery position and during the drum rest period of the rearward stroke of actuator 20. A surface 55 is provided on cam 48 to progressively engage a surface 56 of an actuator guide 57 and a surface 58 of the guide disposed to apply a force to aid spring 46 to return the pawl to drum 26.

As actuator 20 proceeds rearwardly, the possible displacement of rebound is gradually reduced until the pawl is returned' to immediate vicinity of the drum. At this point, the necessary clearance between the guide and the cam would allow the pawl torebound enough to interfere with the `incoming case, but in that position, spring 46 controls pawl 38 to stabilize the pawl into engagement with rear'face 44.

In Fig. 4, actuator Z0 is in battery position with pawl 38 vdisplaced from the normal position thereof by striker 54. Figs. 5 and 6 occur in the rearward stroke of actuator 20 with pawl 3S being urged to normal position by guide surface 58.

In 7, striker 54 is contacting cam 48 in the beginning of extraction. As actuator 20 continues forwardly, cam 48 is rotated but rotation `of the cam is limited by surface 55 and guide surface 56'.

Tests show that the inclusion in the gun of the additional sections of the cam and of the guide increased the`v reliability' of the extraction function. For instance, the life of the pawl spring is increased manyfold by the reduced stress thereon.

While the foregoing is a description of the preferred embodiment, the following claim is intended to include those modifications and variations that are within the spirit and scope of our invention.

We claim:

In an automatic gun including a recoil unit with a rotatable drum thereon including chambers for cartridges and an actuator disposed for slidable reciprocation in rearward and forward strokes :to rotate the cartridges to a ring station for discharge and the cases of the spent cartridges to an extraction station responsive to the discharge, an extraction device comprising an extractor with a pawl and a cam rotatable in the recoil unit and provided with a spring for' biasing said pawl to a normal position Iof projection into the extraction grooves of the extraction station cases, and a striker and a guide on the actuator for respective engagement with said cam, said striker being disposed to rotate said pawl for removal of the cases from the drum, and said guide being disposed to progressively limit the displacement of said pawl from the normal position responsive to the forward and rearward strokes.

References Cited in the tile of this patent UNITED STATES PATENTS 2,656,635y Stevens `et al Oct. 27, 1953 2,708,803 Schneider May 24, i955 FOREIGN PATENTS 693,152 Great Britain June 24, 1953 

